Author: Sune Fischer
Date: 15:57:45 01/22/02
Go up one level in this thread
On January 22, 2002 at 18:45:40, Sean Mintz wrote:
Erhh yeah, I was expecting something like that;)
Seems 0x88 is really fast, except for detecting checks :(
Bitboards can really do the checks quickly, but then extracting the moves with
FirstBit(bb) is relative slow.
I wish I knew what to implement....
-S.
>Test checking is a ripoff of the move generator. I'm working on a program with a
>friend from FICS and making it so it passes positions around as opposed to
>having a global board. This is slower but a lot nicer to work with. This isn't
>exactly pointless rambling, it's just that the function was almost free before
>this --- so it can make life pretty easy.
>
>The 'piece_array_*[*]' are just arrays of offsets for movement.
>
>Here are the functions:
>
>int is_checked(Position * board, int side) {
> if (side == WHITE) {
> return is_attacked(board, board->wk_loc, BLACK);
> } else if (side == BLACK) {
> return is_attacked(board, board->bk_loc, WHITE);
> }
>
> return 1;
>}
>
>int is_attacked(Position * board, int sq, int side) {
> int i,
> j;
>
> for (i=0; i<4; i++) {
> j = sq;
>
> while (!(j & 0x88)) {
> j += piece_array_rook[i];
>
> if (board->color[j] == EMPTY) {
> continue;
> } else if (board->color[j] != side) {
> break;
> } else if ((board->piece[j] == QUEEN) ||
>(board->piece[j] == ROOK)) {
> return 1;
> } else {
> break;
> }
> }
>
> j = sq;
>
> while (!(j & 0x88)) {
> j += piece_array_bishop[i];
>
> if (board->color[j] == EMPTY) {
> continue;
> } else if (board->color[j] != side) {
> break;
> } else if ((board->piece[j] == QUEEN) ||
>(board->piece[j] == BISHOP)) {
> return 1;
> } else {
> break;
> }
> }
> }
>
> for (i=0; i<8; i++) {
> j = sq + piece_array_knight[i];
>
> if ((board->color[j] == side) && (board->piece[j] == KNIGHT)) {
> return 1;
> }
>
> j = sq + piece_array_king[i];
>
> if ((board->color[j] == side) && (board->piece[j] == KING)) {
> return 1;
> }
> }
>
> if (side == WHITE) {
> if ((board->color[sq + 15] == WHITE) && (board->piece[sq + 15]
>== PAWN)) {
> return 1;
> }
> if ((board->color[sq + 17] == WHITE) && (board->piece[sq + 17]
>== PAWN)) {
> return 1;
> }
> } else if (side == BLACK) {
> if ((board->color[sq - 15] == BLACK) && (board->piece[sq - 15]
>== PAWN)) {
> return 1;
> }
> if ((board->color[sq - 17] == BLACK) && (board->piece[sq - 17]
>== PAWN)) {
> return 1;
> }
> }
>
> return 0;
>}
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